SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '584a578b11b66b903f50a8af95338e52cbff532d0f2fcecd138fac74ab048ecc' 
  AND token = 'AB8dOksgLM+0scl2RgfvYdclHhzgJXsAROOQPzQLOH4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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