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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '40a21c2b93eb85ac72a4b8c497f29779e7cbb983fc70a31055623e5a21fceec4' 
  AND token = 'HOxg6Q39jUni9smB2zzIwKedd3obd2E7ITom0ytDfJQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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