SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a14766f0df316fe7618c42f6bd04a6272e4ed2f420ec63f81c38ce2723357188' 
  AND token = 'hcqO1ZFg7dsb1KJE9JF1MpmRp9PErNRCqksQMV2hUw4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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