SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c1933fffe4bb270c3a403cca51d738f9f8bc756c0fd819e747ee437f2819121' 
  AND token = 'S4qVsh33Kkjchv95Jod+q3kFwld2AfAI/hbLVUGDOFE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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