SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '96c0a387d69f3b0658fdb223a6ba31bb72773b0d71e7fad1a08ef8f1cbe40b3a' 
  AND token = 'mphBj7cXh/wwVj8FAJ7AI994s/HKFyxFVBG4GptQjD4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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