SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '318fecc75f7d24f14af8395a930b0c2cec5a9116d590df6758ac06045939f11c' 
  AND token = 'k61ntYdszo9EPxtnbeYZSbeGV/BK1sXlfCzs+w4ssAY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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