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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '18a360d81b17b109b529f03e93d14e95d49b2d619fed0d6b8091981ef0b84dba' 
  AND token = 'DG4mG81ru8xZZ6wEAz3Spr/reIyJhdNDxO4kQncjA78=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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