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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a68e1ef826064096c7a71320abb0d9bd995d9cb2dd939847afc92603f38efad' 
  AND token = '6krk4C412YFJXg3DEFXXk9vXTZdtKYWsMicfMv7/+Rs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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