SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8729588456ec47024da4b78bad353dee4246ff8626b1d5385336221111da2a2' 
  AND token = '5GNCZAJyAbsuwoRmMT1Tn6TvCoHpyLyyyQgFDUWIxOA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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