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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd75ddd0d2639f5e46bd62c4c393131974936bdfa4ddb2d8b78a5df6aebb4b31f' 
  AND token = '3QcOW3vD368Kny+sP994Z1Hj7kwny30tnfGrC4v77eM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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