SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '687c93d0594495e1efbb20c235c534004e8e15dc50a236b519853fd8803df5a3' 
  AND token = '9IGGXUPzyf5LqmjrHJXieEuah6bPGMJ2wG5RWeeAPX8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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