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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e4f20d3c207dfa1ebb945a3309ad3ef663b6f987a2736bba2f3ee665f2f7c8d3' 
  AND token = '71XEuvmsnGWOS2dSfJUXpO0hy5S9IPgFM5Nyq7U1T/w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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