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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac7fc372b231f608f27cb8015ca518dd7c0561c65e337fd0d8bdd8ca5d28a79b' 
  AND token = 'gRQqTZHrdfxYYbsjUERJwVR7E/HzNw/Ey3E1FkCSbSs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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