SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e2c75120a809975dbb9a14b69672ac56ac62813a0b63de9e862287a585b3474c' 
  AND token = 'pLjuXybBoF2URcG34oZCCap7GldF0HS6zu8vtJ8aOAY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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