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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '75f8d7c5684fb529947d2f01cd020db6e48fc53a5b1e90dd7f402d86ab551f0e' 
  AND token = 'ukQculKcg0DmlyYZ3oLKPKTSLXsRJmvoGQSivn3NxdQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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