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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9b2fa5c54fdae869401bc151f4f23b3a4d39979e75d58cb6c10c42c57e3fc4a1' 
  AND token = '6z1/Ca5kMsXLnrLDYNu2yAZv7nUpTyM7/WnkpcWlV2c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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