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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef5c11d32752e177f71a1b2621bb6ff835bd518231cdf111091076d2a52476b0' 
  AND token = 'fNYC2KGV92aZf9TlluLHxhyae67i+v+wDEDpijdGZLo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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