SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c51033f83f00cc0fea7c2342eafa8d56b2488a6529e6d3ee39b4200eb453cc4d' 
  AND token = 'ICNzF7d4FjAbnUtYyBQif3VZWq8SMLcBQF3x+/r8uMg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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