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SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '3d6ee5dd46e2cad1b6aaa56874518ee38752d7b888d8fb182b53209f20ff8e53' 
  AND token = 'I1/RwwXCM8dwJ9pSevKAq3WirFZQ+W1LT2PZIDb4DQc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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