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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6493696dbfc5d3eaf1df4df35fa7288ad0c0e1a8f1894350215b00e7ea492b9' 
  AND token = 'a4Y1ywlS9ZiLqWoWM2PyTxiJwRo+iBrSWw1XRg1+ALk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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