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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b337cbe6edefaf3fc6a10ad23f42a05cce8f38c7ef92a05b23c4982f267d42f3' 
  AND token = 'rktHtwecIuMc9hP9HdhGlo01y+SuDCeNkTriQVs7B3s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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