SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7fe8128a993d2c7db51ed5fd84f5062b496c1d30def504db3c3f9895f7228f6' 
  AND token = '0D57+JMJq1Vr0/lgOfNUFlHjCv3zCkCJV5ljceuFP5Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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