SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a45f26cf06d62724b569841095593d8c599f27084317da12932252985fa491ba' 
  AND token = '+HB8ONSTgCGSh9rXfNNMu08vlNUbT0EnwRi/N1RsCuY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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