SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e872cc63d1415278e8ed77bab848bb38768e1e8425affc23dc55fd920681fb59' 
  AND token = 'OOp3ryEuNjLT9LlDydkNQy+NgNrcd8M4HfUxN6vdWKs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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