SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '390555b684bedb3d7dce885e3d6b0e35e2bd616d2b142295c6a3e20065393ecc' 
  AND token = 'KO6EjGcK1NA+o3vFAIB3AFc/2fvH2eLL659hCrSd7J4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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