SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '355ecbfda73341820d01bc46af4c6333fe2a60326786ba8cc95cc488a163d10c' 
  AND token = 'I1xJns5y3LBdTmx37OR2JGSEKoWMfOcujsTToeNANSo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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