SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f45fc6b7d3235fe7867e4100623d2c64bdaa251b12f7fa408a0730063d91e12' 
  AND token = 'b6DYE6MUQv9iCRht8mEpeLHgmZeyEjxuBeRAFdSqFRU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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