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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'db2e19f7a1ea948a386fa98ea0d6cac27438d375611c8fa599a2534e3fbb8d3b' 
  AND token = 'cYbLNyZv1HgAArr2+KZb6WQmKNeb/QuEUbB7sYRmaXs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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