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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75da44bc884267f0544d37bb61f7a91c49329e3fad58cbf88d85fecbdfba760d' 
  AND token = 'nvLY4KDUPWwWBmmCmI1D4d2WH8KwAEE5yMmEz/wEE+Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}