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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '1fa0c86e63c48231038f0877a77cd4fa3121d712bd49ad6d1f12795996ccb5e7' 
  AND token = 'M/Z42RwJaRauQLyOm9lLjJuuJD8flHrFGkujMaBidDg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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