SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c71362743451937527a311d82bb44de2fe5848b27c78ee6138bb5089a80e9b73' 
  AND token = 'nlsvLhpIzvPr/ipiZz6ZaDzBJgXcFOPINrLe22BhPqY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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