SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1852eb4de5755b6bb989031879c1652570f49e7edffb1d09ce6d1ddc4c23fbb1' 
  AND token = '9KFUnHDSKenXz+m6cB5wb/8akzZgqBNWcFXJ5BaMPa8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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