SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c3e15030ab39346b93075bc6983a75388c272adda8192e26bbba4f6a413e390' 
  AND token = 'BBOa/ENfSoesJmmQ9XLOM0FCC2U22YjZ4wLYoc/LWg4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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