SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1978d0805596bcb34cf009547361dc51f5fb4e0c71f3b7c822103218df5fd13d' 
  AND token = 'B6CW+BZSTxbHysvUFUVPPv67NTnhrOIc/bvnjW31t58=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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