SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfcc26f5e285b5dbfa488dc83918500d0fe0078ade1f765362130d508a49c10b' 
  AND token = 'ErSwLR65cOPmNmwiqwLPYry8+HsTYy+DByHEMhYB7Mc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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