SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35387a6687d076e65f75aef9ec3caf5131471bdcfb922b1f5f720b6a4a99da78' 
  AND token = 'U5GrpcixqYZ/XjWkpsloAfoRXWA+Wb1XPuaRK17AEAc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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