SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf7f70bd61b156da021b7f98d0ae958ccdcb36321557f3fac350e187a1d7ed35' 
  AND token = 'JR+ElxN8f/KAisyR9NKFtoBA/2OFjGI+QYVXZLu6gSY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}